CGM Continuous Glucose Monitor Denied: Appeal

Continuous glucose monitors (CGMs) — including the Dexcom G7, Abbott FreeStyle Libre 3, and Medtronic Guardian — have transformed diabetes management. CGMs provide real-time glucose readings every few minutes, allowing people with diabetes to respond to trends before dangerous highs or lows occur. Despite their proven clinical benefits, CGMs are frequently denied by insurers due to Prior Authorization Denied: How to Appeal" class="auto-link">prior authorization failures, eligibility disputes, or outdated coverage policies.

How CGM Coverage Expanded

For years, Medicare and many private insurers limited CGM coverage to patients with Type 1 diabetes or insulin-requiring Type 2 diabetes with demonstrated hypoglycemia. In 2023, CMS significantly expanded Medicare CGM coverage criteria.

Current Medicare Coverage (2023 expanded criteria):

• Patients with Type 1 or Type 2 diabetes who:
  • Use any type of insulin (multiple daily injections or an insulin pump), OR
  • Have a history of hypoglycemia (problematic low blood sugar)
• The 2023 expansion notably removed the requirement for a certain number of daily insulin injections
• Type 2 patients on non-insulin therapy with hypoglycemia history can also qualify

This is a significant expansion from prior rules that required at least three insulin injections per day.

Private Insurance: Private insurer coverage varies widely. Many commercial plans now follow similar expanded criteria, but some still use older, more restrictive criteria. Always check your specific plan's CGM coverage policy.

State CGM Mandates

More than 20 states have enacted laws requiring commercial insurance plans to cover CGMs for patients with diabetes. States with CGM coverage mandates as of 2026 include California, Colorado, New York, Illinois, Texas, New Jersey, and others. Coverage mandates typically require:

• Coverage without step therapy or formulary restrictions
• Limits on cost-sharing (some states cap CGM copays)
• Coverage for both Type 1 and Type 2 patients meeting clinical criteria

If you live in a state with a CGM mandate and your plan is fully insured (not self-funded), your insurer must comply. Check your state insurance commissioner's website or contact a patient advocacy group for your state's specific CGM laws.

Common Denial Reasons and Responses

Denial reason: "Diagnosis code does not meet criteria" Your plan may have outdated criteria. Request the specific clinical coverage policy and compare it to current ADA guidelines. If the criteria are outdated (pre-2023 expansion), cite the Medicare expansion and ADA Standards of Medical Care as evidence of the current standard of care.

Denial reason: "Prior authorization requirements not met" Your doctor's office may not have submitted all required documentation. Contact the office immediately and ask them to resubmit with:

• Your most recent A1C
• Hypoglycemia history or documentation
• Insulin regimen details
• A letter of medical necessity

Denial reason: "Not medically necessary" Appeal with documentation from the American Diabetes Association (ADA) Standards of Medical Care in Diabetes, which recommends CGM for all patients with diabetes using insulin and for patients with hypoglycemia. The ADA guidelines carry significant weight in appeal determinations.

Denial reason: "Device not on formulary" If your specific CGM (e.g., Dexcom G7) is not on the formulary but another is, your doctor can request a formulary exception if there is a clinical reason for the specific device — integration with an insulin pump, better accuracy for your clinical needs, or prior device experience.

How to Appeal a CGM Denial

Step 1: Get the specific denial reason. Read the denial letter and note every cited criterion.

Step 2: Contact your prescribing physician. Ask for a letter of medical necessity that:

• Documents your diagnosis and insulin/medication regimen
• Describes any hypoglycemic events or episodes
• Explains why CGM is clinically appropriate for you
• Cites ADA guidelines supporting CGM use in your situation

Step 3: Pull your glucose history. Meter downloads showing hypoglycemic events strengthen the medical necessity argument. If you have had emergency hypoglycemia, include those records.

Step 4: Research your state's CGM laws. If you are in a state with a CGM mandate, include this in your appeal as a legal basis for coverage.

Step 5: Submit the internal appeal with the medical necessity letter, supporting records, and relevant clinical guidelines.

Step 6: External Independent Review: Complete Guide" class="auto-link">External review. If denied internally, the external reviewer applies clinical standards — including current ADA guidelines — not the insurer's proprietary criteria.

Medicare-Specific Steps

For Medicare denials:

• Ensure the prescribing physician is enrolled in Medicare and the order meets the updated coverage criteria
• Ensure the CGM supplier is a Medicare-enrolled DME supplier
• If denied, file a Redetermination request with your Medicare Administrative Contractor (MAC) within 120 days

Manufacturer Patient Assistance

If coverage is denied and you cannot afford the out-of-pocket cost:

• Dexcom: Dexcom Access Program for eligible patients
• Abbott: myfreestyle.com assistance programs
• Medtronic: Access and affordability programs through Medtronic

These programs can provide CGM supplies at reduced or no cost while your appeal is pending.

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Related Reading:

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Internal vs External Insurance Appeal